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Commit ae3d89a7 authored by Dan Streetman's avatar Dan Streetman Committed by Linus Torvalds
Browse files

zswap: allow initialization at boot without pool 

Allow zswap to initialize at boot even if it can't create its pool due
to a failure to create a zpool and/or compressor.  Allow those to be
created later, from the sysfs module param interface.

Link: http://lkml.kernel.org/r/20170124200259.16191-3-ddstreet@ieee.org


Signed-off-by: default avatarDan Streetman <dan.streetman@canonical.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 01cddfe9

mm/zswap.c

+34 −12
Original line number Diff line number Diff line
@@ -185,6 +185,9 @@ static bool zswap_init_started; 
/* fatal error during init */

static bool zswap_init_failed;



/* init completed, but couldn't create the initial pool */

static bool zswap_has_pool;



/*********************************

* helpers and fwd declarations

**********************************/
@@ -424,7 +427,8 @@ static struct zswap_pool *__zswap_pool_current(void) 
	struct zswap_pool *pool;



	pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);

	WARN_ON(!pool);

	WARN_ONCE(!pool && zswap_has_pool,

		  "%s: no page storage pool!\n", __func__);



	return pool;

}
@@ -443,7 +447,7 @@ static struct zswap_pool *zswap_pool_current_get(void) 
	rcu_read_lock();



	pool = __zswap_pool_current();

	if (!pool || !zswap_pool_get(pool))

	if (!zswap_pool_get(pool))

		pool = NULL;



	rcu_read_unlock();
@@ -459,7 +463,9 @@ static struct zswap_pool *zswap_pool_last_get(void) 


	list_for_each_entry_rcu(pool, &zswap_pools, list)

		last = pool;

	if (!WARN_ON(!last) && !zswap_pool_get(last))

	WARN_ONCE(!last && zswap_has_pool,

		  "%s: no page storage pool!\n", __func__);

	if (!zswap_pool_get(last))

		last = NULL;



	rcu_read_unlock();
@@ -582,6 +588,9 @@ static void zswap_pool_destroy(struct zswap_pool *pool) 


static int __must_check zswap_pool_get(struct zswap_pool *pool)

{

	if (!pool)

		return 0;



	return kref_get_unless_zero(&pool->kref);

}
@@ -639,7 +648,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp, 
	}



	/* no change required */

	if (!strcmp(s, *(char **)kp->arg))

	if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)

		return 0;



	/* if this is load-time (pre-init) param setting,
@@ -685,6 +694,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp, 
	if (!ret) {

		put_pool = zswap_pool_current();

		list_add_rcu(&pool->list, &zswap_pools);

		zswap_has_pool = true;

	} else if (pool) {

		/* add the possibly pre-existing pool to the end of the pools

		 * list; if it's new (and empty) then it'll be removed and
@@ -692,6 +702,15 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp, 
		 */

		list_add_tail_rcu(&pool->list, &zswap_pools);

		put_pool = pool;

	} else if (!zswap_has_pool) {

		/* if initial pool creation failed, and this pool creation also

		 * failed, maybe both compressor and zpool params were bad.

		 * Allow changing this param, so pool creation will succeed

		 * when the other param is changed. We already verified this

		 * param is ok in the zpool_has_pool() or crypto_has_comp()

		 * checks above.

		 */

		ret = param_set_charp(s, kp);

	}



	spin_unlock(&zswap_pools_lock);
@@ -724,6 +743,10 @@ static int zswap_enabled_param_set(const char *val, 
		pr_err("can't enable, initialization failed\n");

		return -ENODEV;

	}

	if (!zswap_has_pool && zswap_init_started) {

		pr_err("can't enable, no pool configured\n");

		return -ENODEV;

	}



	return param_set_bool(val, kp);

}
@@ -1205,22 +1228,21 @@ static int __init init_zswap(void) 
		goto hp_fail;



	pool = __zswap_pool_create_fallback();

	if (!pool) {

		pr_err("pool creation failed\n");

		goto pool_fail;

	}

	if (pool) {

		pr_info("loaded using pool %s/%s\n", pool->tfm_name,

			zpool_get_type(pool->zpool));



		list_add(&pool->list, &zswap_pools);

		zswap_has_pool = true;

	} else {

		pr_err("pool creation failed\n");

		zswap_enabled = false;

	}



	frontswap_register_ops(&zswap_frontswap_ops);

	if (zswap_debugfs_init())

		pr_warn("debugfs initialization failed\n");

	return 0;



pool_fail:

	cpuhp_remove_state_nocalls(CPUHP_MM_ZSWP_POOL_PREPARE);

hp_fail:

	cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);

dstmem_fail: